Field experiments were carried out in four successive seasons (2015 to 2018) at the experimental farm of faculty of
agriculture, Menoufia University, in Shebin El-Kom, Egypt. The main objectives of this study were to study the effect of
water stress on different maize traits and identify the effectiveness of S1 recurrent selection for improving drought
tolerance in Tep#5 population (white). 100 S1's were isolated and evaluated under normal irrigation (NI) and drought
stress (DS) at flowering stage. The highest yielding 10 lines (10%) selected under each environment were random mated
by bulking pollen and make crosses handly. Two sub-populations were obtained (Tep#5-NI and Tep#5-DS).The
population (Tep#5-NI) along with the original population (Tep#5) were evaluated for 19 traits under normal irrigation
condition (NI) and the population (Tep#5-DS) along with the original population (Tep#5) were evaluated under drought
stress condition (DS) in a randomized complete block design with four replications. Results indicated wide genetic
variation among S1 progenies for most studied traits under both selection environments (NI and DS). Heritability estimates
were generally higher under drought stress than under normal irrigation conditions. Number of kernels/row, 100-kernels
weight and ear length traits were predicted to grain yield more efficiently under drought stress than under normal irrigation
conditions. One cycle of S1 recurrent selection under water-stress caused a significant actual improvement of grain yield of
the newly developed population (Tep#5-DS) over its original population (Tep#5) of 15.47%. The improved population
Tep#5-NI developed by using normal irrigation as a selection environment showed significant actual improvements in
grain yield under normal irrigation (12.46%) environment. Selection under water stressed and non-stressed irrigations
were efficient in improving grain yield.